Question

A three-point testcross is often used to

a)determine whether mutations occur at the same or at different loci
b)determine if chromosome mutations are present
c)do a complementation test
d)isolate mutations affecting a particular trait
e)efficiently map genes

Answer 1

The test cross is used to determine whether an organism expressing a dominant trait is a homozygote or a heterozygote.

Step-by-step explanation:

The test cross is used to determine whether an organism that expresses a dominant trait is a homozygote or a heterozygote. It involves crossing the dominant-expressing organism with an organism that is homozygous recessive for the same characteristic. If the dominant-expressing organism is a homozygote, all the offspring will be heterozygotes expressing the dominant trait. On the other hand, if the dominant-expressing organism is a heterozygote, the offspring will exhibit a 1:1 ratio of heterozygotes and recessive homozygotes.